Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/004—Photosensitive materials
  • G03F7/039—Macromolecular compounds which are photodegradable, e.g. positive electron resists
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F20/00—Homopolymers and copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride, ester, amide, imide or nitrile thereof
  • C08F20/02—Monocarboxylic acids having less than ten carbon atoms, Derivatives thereof
  • C08F20/10—Esters
  • C08F20/22—Esters containing halogen
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F22/00—Homopolymers and copolymers of compounds having one or more unsaturated aliphatic radicals each having only one carbon-to-carbon double bond, and at least one being terminated by a carboxyl radical and containing at least one other carboxyl radical in the molecule; Salts, anhydrides, esters, amides, imides or nitriles thereof
  • C08F22/10—Esters
  • C08F22/12—Esters of phenols or saturated alcohols
  • C08F22/18—Esters containing halogen
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F22/00—Homopolymers and copolymers of compounds having one or more unsaturated aliphatic radicals each having only one carbon-to-carbon double bond, and at least one being terminated by a carboxyl radical and containing at least one other carboxyl radical in the molecule; Salts, anhydrides, esters, amides, imides or nitriles thereof
  • C08F22/36—Amides or imides
  • C08F22/40—Imides, e.g. cyclic imides
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F32/00—Homopolymers and copolymers of cyclic compounds having no unsaturated aliphatic radicals in a side chain, and having one or more carbon-to-carbon double bonds in a carbocyclic ring system
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/004—Photosensitive materials
  • G03F7/0046—Photosensitive materials with perfluoro compounds, e.g. for dry lithography
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
  • C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
  • C08F220/10—Esters
  • C08F220/22—Esters containing halogen
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F232/00—Copolymers of cyclic compounds containing no unsaturated aliphatic radicals in a side chain, and having one or more carbon-to-carbon double bonds in a carbocyclic ring system
  • C08F232/02—Copolymers of cyclic compounds containing no unsaturated aliphatic radicals in a side chain, and having one or more carbon-to-carbon double bonds in a carbocyclic ring system having no condensed rings
  • C08F232/04—Copolymers of cyclic compounds containing no unsaturated aliphatic radicals in a side chain, and having one or more carbon-to-carbon double bonds in a carbocyclic ring system having no condensed rings having one carbon-to-carbon double bond
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F232/00—Copolymers of cyclic compounds containing no unsaturated aliphatic radicals in a side chain, and having one or more carbon-to-carbon double bonds in a carbocyclic ring system
  • C08F232/08—Copolymers of cyclic compounds containing no unsaturated aliphatic radicals in a side chain, and having one or more carbon-to-carbon double bonds in a carbocyclic ring system having condensed rings
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
  • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
  • G03F7/004—Photosensitive materials
  • G03F7/0045—Photosensitive materials with organic non-macromolecular light-sensitive compounds not otherwise provided for, e.g. dissolution inhibitors

Definitions

• This invention relates to polymers useful as the base resin in resist compositions, especially chemical amplification resist compositions, suited for microfabrication. It also relates to resist compositions comprising the polymers, and a patterning process using the same.
• the pattern rule is made drastically finer.
• the rapid advance toward finer pattern rules is grounded on the development of a projection lens with an increased NA, a resist material with improved performance, and exposure light of a shorter wavelength.
• acid-catalyzed chemical amplification positive working resist materials are effective as disclosed in USP 4,491,628 and USP 5,310,619 (JP-B 2-27660 and JP-A 63-27829). They now become predominant resist materials especially adapted for deep UV lithography.
• the change-over from i-line (365 nm) to shorter wavelength KrF laser (248 nm) brought about a significant innovation.
• Resist materials adapted for KrF excimer lasers enjoyed early use on the 0.30 micron process, went through the 0.25 micron rule, and currently entered the mass production phase on the 0.18 micron rule. Engineers have started investigation on the 0.15 micron rule, with the trend toward a finer pattern rule being accelerated.
• An object of the invention is to provide novel polymers useful as base polymers in resist compositions, preferably having a high transmittance to vacuum ultraviolet radiation in the wavelength range up to 300nm, and preferably any one or more of F 2 excimer laser beam (157 nm), Kr 2 excimer laser beam (146 nm), KrAr excimer laser beam (134 nm) and Ar 2 excimer laser beam (121 nm).
• Other aspects are novel resist compositions comprising such polymers, and patterning processes using them.
• the invention provides a polymer having groups of the following general formula (1).
• R 1 , R 2 , R 3 and R 4 are independently hydrogen, fluorine or unsubstituted or fluorinated, straight, branched or cyclic alkyl groups of 1 to 20 carbon atoms, and at least one of R 1 , R 2 , R 3 and R 4 is or contains fluorine.
• the polymer includes recurring units represented by the following general formula (2-1), (2-2), (2-3), (2-4) or (2-5).
• R 1 to R 4 are as defined above;
• R 5 , R 6 and R 7 are independently hydrogen, fluorine or unsubstituted or fluorinated, straight, branched or cyclic alkyl groups of 1 to 20 carbon atoms;
• R 8 and R 9 are independently hydrogen, methyl or CH 2 CO 2 R 11 ;
• R 10 is an unsubstituted or fluorinated, straight, branched or cyclic alkylene group of 1 to 20 carbon atoms;
• R 11 is a substituted or unsubstituted, straight, branched or cyclic alkyl group of 1 to 20 carbon atoms; and
• k is equal to 0 or 1.
• the invention provides a resist composition comprising polymer as defined above.
• One embodiment of the invention is a chemical amplification, positive resist composition comprising (A) the polymer defined above, (B) an organic solvent, and (C) a photoacid generator.
• the resist composition further includes a basic compound and/or a dissolution inhibitor.
• the invention provides a process for forming a pattern, comprising the steps of (1) applying the chemical amplification resist composition defined above onto a substrate to form a coating; (2) heat treating the coating and exposing the coating to high energy radiation with a wavelength of up to 300 nm or electron beam through a photo-mask; (3) optionally heat treating the exposed coating, and developing the coating with a developer.
• a polymer obtained by introducing fluorine into an acrylic resin or a polymer comprising as the backbone an aliphatic cyclic compound originating from a norbornene derivative has been found to have a minimized absorption at the desired wavelength and eliminate the negative working problem.
• an ester polymer having fluorinated alkyl groups introduced therein not only has a further enhanced transmittance in proximity to 157 nm, but is so acid labile that the effect of enhancing the contrast of alkali dissolution is exerted.
• the polymer or high molecular weight compound is defined as having groups of the following general formula (1), particularly in which the -O is of an ester group, and especially recurring units of any of the following general formulas (2-1) to (2-5).
• Units of formula (1) e.g. (2) preferably constitute at least 10mol%, more preferably at least 20 or 30mol%, of monomer residues in the polymer.
• R 1 , R 2 , R 3 and R 4 are independently hydrogen, fluorine or unsubstituted or fluorinated, straight, branched or cyclic alkyl groups of 1 to 20 carbon atoms, and at least one of R 1 , R 2 , R 3 and R 4 contains fluorine.
• R 5 , R 6 and R 7 are independently hydrogen, fluorine or unsubstituted or fluorinated, straight, branched or cyclic alkyl groups of 1 to 20 carbon atoms;
• R 8 and R 9 are independently hydrogen, methyl or CH 2 CO 2 R 11 ;
• R 10 is an unsubstituted or fluorinated, straight, branched or cyclic alkylene group of 1 to 20 carbon atoms;
• R 11 is a substituted or unsubstituted, straight, branched or cyclic alkyl group of 1 to 20 carbon atoms; and k is equal to 0 or 1.
• the straight, branched or cyclic alkyl groups are those of 1 to 20 carbon atoms, preferably 1 to 12 carbon atoms, and more preferably 1 to 10 carbon atoms, including methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, cyclopentyl, cyclohexyl, 2-ethylhexyl, and n-octyl.
• the fluorinated alkyl groups correspond to the foregoing alkyl groups in which some, most or all hydrogen atoms are replaced by fluorine atoms and include, for example, trifluoromethyl, 2,2,2-trifluoroethyl, 3,3,3-trifluoropropyl, and 1,1,2,2,3,3,3-heptafluoropropyl.
• the substituted alkyl groups are typically the fluorinated alkyl groups described just above, though not limited thereto. Groups described as 'unsubstituted or fluorinated' may also be substituted, e.g. with other halogens, but this is not preferred.
• alkylene groups of 1 to 20 carbon atoms and fluorinated alkylene groups of 1 to 20 carbon atoms correspond to the foregoing alkyl groups and fluorinated alkyl groups of 1 to 20 carbon atoms, with one hydrogen atom being eliminated therefrom, and they are preferably of 1 to 12 carbon atoms, and especially 1 to 10 carbon atoms.
• Illustrative examples of the group of above formula (1) include groups of the following formulas (3-1) to (3-3).
• recurring units of any of the following formulas (4) through (39) may be introduced into the inventive polymer in addition to the above-described units.
• R 5 , R 6 and R 7 are as defined above.
• recurring units having fluorine-free acid labile groups may be introduced into the inventive polymer.
• R 5 to R 10 and k are as defined above, R is an acid labile group.
• the acid labile group represented by R is selected from a variety of such groups, preferably from among the groups of the following formulas (40) and (41), tertiary alkyl groups with 4 to 40 carbon atoms of the following formula (42), trialkylsilyl groups whose alkyl groups each have 1 to 6 carbon atoms, and oxoalkyl groups of 4 to 20 carbon atoms.
• R 12 is a tertiary alkyl group of 4 to 20 carbon atoms, preferably 4 to 15 carbon atoms, a trialkylsilyl group whose alkyl groups each have 1 to 6 carbon atoms, an oxoalkyl group of 4 to 20 carbon atoms or a group of formula (42).
• Exemplary tertiary alkyl groups are tert-butyl, tert-amyl, 1,1-diethylpropyl, 1-ethylcyclopentyl, 1-butylcyclopentyl, 1-ethylcyclohexyl, 1-butylcyclohexyl, 1-ethyl-2-cyclopentenyl, 1-ethyl-2-cyclohexenyl, and 2-methyl-2-adamantyl.
• Exemplary trialkylsilyl groups are trimethylsilyl, triethylsilyl, and dimethyl-tert-butylsilyl.
• Exemplary oxoalkyl groups are 3-oxocyclohexyl, 4-methyl-2-oxooxan-4-yl, and 5-methyl-5-oxooxoran-4-yl.
• Letter "a” is an integer of 0 to 6.
• R 13 and R 14 are independently hydrogen or straight, branched or cyclic alkyl groups of 1 to 18 carbon atoms, preferably 1 to 10 carbon atoms, for example, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, cyclopentyl, cyclohexyl, 2-ethylhexyl and n-octyl.
• R15 is a monovalent hydrocarbon group of 1 to 18 carbon atoms, preferably 1 to 10 carbon atoms, which may have a hetero atom (e.g., oxygen atom), for example, straight, branched or cyclic alkyl groups, and such groups in which some hydrogen atoms are replaced by hydroxyl, alkoxy, oxo, amino or alkylamino groups.
• a hetero atom e.g., oxygen atom
• a pair of R 13 and R 14 , a pair of R 13 and R 15 , or a pair of R 14 and R 15 , taken together, may form a ring.
• Each of R 13 , R 14 and R 15 is a straight or branched alkylene group of 1 to 18 carbon atoms, preferably 1 to 10 carbon atoms, when they form a ring.
• acid labile groups of formula (40) include tert-butoxycarbonyl, tert-butoxy-carbonylmethyl, tert-amyloxycarbonyl, tert-amyloxycarbonylmethyl, 1,1-diethylpropyloxycarbonyl, 1,1-diethylpropyloxycarbonylmethyl, 1-ethylcyclopentyloxycarbonyl, 1-ethylcyclopentyloxycarbonylmethyl, 1-ethyl-2-cyclopentenyloxycarbonyl, 1-ethyl-2-cyclopentenyloxycarbonylmethyl, 1-ethoxyethoxycarbonylmethyl, 2-tetrahydropyranyloxycarbonylmethyl, and 2-tetrahydrofuranyloxycarbonylmethyl.
• illustrative examples of the cyclic groups include tetrahydrofuran-2-yl, 2-methyltetrahydrofuran-2-yl, tetrahydropyran-2-yl and 2-methyltetrahydropyran-2-yl.
• Preferred among the groups of formula (41) are ethoxyethyl, butoxyethyl and ethoxypropyl.
• R 16 , R 17 and R 18 are independently monovalent hydrocarbon groups, for example, straight, branched or cyclic alkyl groups of 1 to 20 carbon atoms, which may contain a hetero atom such as oxygen, sulfur, nitrogen or fluorine.
• a pair of R 16 and R 17 , a pair of R 16 and R 18 , or a pair of R 17 and R 18 , taken together, may form a ring.
• Examples of the tertiary alkyl group represented by formula (42) include tert-butyl, triethylcarbyl, 1-ethylnorbornyl, 1-methylcyclohexyl, 1-ethylcyclopentyl, 2-(2-methyl)adamantyl, 2-(2-ethyl)adamantyl, and tert-amyl.
• R 19 is a straight, branched or cyclic alkyl group of 1 to 6 carbon atoms, for example, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, n-pentyl, n-hexyl, cyclopropyl, cyclopropylmethyl, cyclobutyl, cyclopentyl or cyclohexyl.
• R 20 is a straight, branched or cyclic alkyl group of 2 to 6 carbon atoms, for example, ethyl, propyl, isopropyl, n-butyl, sec-butyl, n-pentyl, n-hexyl, cyclopropyl, cyclopropylmethyl, cyclobutyl, cyclopentyl or cyclohexyl.
• R 21 is hydrogen, a monovalent hydrocarbon group of 1 to 6 carbon atoms which may contain a hetero atom, or a monovalent hydrocarbon group of 1 to 6 carbon atoms which may be separated by a hetero atom.
• R 22 is hydrogen or an alkyl, hydroxyalkyl, alkoxy or alkoxyalkyl group of 1 to 20 carbon atoms, especially 1 to 16 carbon atoms, which may be straight, branched or cyclic.
• Illustrative examples include methyl, hydroxymethyl, ethyl, hydroxyethyl, propyl, isopropyl, n-butyl, sec-butyl, n-pentyl, n-hexyl, methoxy, methoxymethoxy, ethoxy, and tert-butoxy.
• the trialkylsilyl groups whose alkyl groups each have 1 to 6 carbon atoms include trimethylsilyl, triethylsilyl, and tert-butyldimethylsilyl.
• the oxoalkyl groups of 4 to 20 carbon atoms include 3-oxocyclohexyl and similar groups.
• the polymer of the invention may be prepared using an essential monomer having a carbon-to-carbon double bond and a group of formula (1) and optionally, other monomer e.g. to provide units of one of formulas (4) to (39) and/or additional monomer to provide units of one or more of formulas (i) to (v).
• an essential monomer usable herein is a monomer to provide recurring units of one of formulas (2-1) to (2-5), for example, a monomer of the following formula to provide recurrinq units of formula (2-1).
• the polymer or high molecular weight compound is generally prepared by mixing the above-mentioned essential monomer and optional monomers with a solvent, adding a catalyst thereto, and effecting polymerization reaction while heating or cooling the system if necessary.
• the polymerization reaction depends on the type of initiator or catalyst, trigger means (including light, heat, radiation and plasma), and polymerization conditions (including temperature, pressure, concentration, solvent, and additives).
• trigger means including light, heat, radiation and plasma
• polymerization conditions including temperature, pressure, concentration, solvent, and additives.
• Commonly used for the polymerization of the monomer are radical polymerization of triggering polymerization with radicals of ⁇ , ⁇ '-azobisisobutyronitrile (AIBN) or the like, and ion (anion) polymerization using catalysts such as alkyl lithium.
• AIBN ⁇ , ⁇ '-azobisisobutyronitrile
• ion (anion) polymerization using catalysts such as alkyl lithium.
• A denotes units having a group of formula (1)
• B denotes units of formulas (4) to (39)
• C denotes units of formulas (i) to (v)
• a preferred polymer is representable by the following formula.
• A a (B) b (C) c
• "a” is a positive number
• "b” and “c” are 0 or positive numbers, and preferably satisfy the following range.
• the polymer of the invention preferably has a weight average molecular weight of about 1,000 to 1,000,000, and especially about 2,000 to 100,000.
• the polymer of the invention is useful as a base resin in resist compositions, typically chemical amplification type resist compositions, and especially chemical amplification type positive resist compositions.
• a second aspect of the invention is a resist composition comprising the polymer defined above.
• the invention provides a chemical amplification positive resist composition
• a chemical amplification positive resist composition comprising (A) the polymer defined above as a base resin, (B) an organic solvent, and (C) a photoacid generator.
• the resist composition may further contain (D) a basic compound and/or (E) a dissolution inhibitor.
• the organic solvent used as component (B) in the invention may be any organic solvent in which the photoacid generator, base resin (inventive polymer), dissolution inhibitor, and other components are soluble.
• the organic solvent include ketones such as cyclohexanone and methyl-2-n-amylketone; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, and 1-ethoxy-2-propanol; ethers such as propylene glycol monomethyl ether, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, propylene glycol dimethyl ether, and diethylene glycol dimethyl ether; and esters such as propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, ethyl lactate, ethyl pyruvate, but
• fluorinated organic solvents examples include 2-fluoroanisole, 3-fluoroanisole, 4-fluoroanisole, 2,3-difluoroanisole, 2,4-difluoroanisole, 2,5-difluoroanisole, 5,8-difluoro-1,4-benzodioxane, 2,3-difluorobenzyl alcohol, 1,3-difluoro-2-propanol, 2',4'-difluoropropiophenone, 2,4-difluorotoluene, trifluoro-acetaldehyde ethyl hemiacetal, trifluoroacetamide, trifluoroethanol, 2,2,2-trifluoroethyl butyrate, ethyl heptafluorobutyrate, ethyl heptafluorobutylacetate, ethyl hexafluoroglutarylmethyl, ethyl 3-hydroxy-4
• organic solvents preferred are diethylene glycol dimethyl ether and 1-ethoxy-2-propanol, in which the photoacid generator is most soluble, and propylene glycol monomethyl ether acetate which is safe, and mixtures thereof.
• the organic solvent is typically used in an amount of about 200 to 5,000 parts by weight per 100 parts by weight of the base resin.
• Suitable examples of the photoacid generator (C) include onium salts of general formula (59) below, diazomethane derivatives of formula (60), glyoxime derivatives of formula (61), ⁇ -ketosulfone derivatives, disulfone derivatives, nitrobenzylsulfonate derivatives, sulfonic acid ester derivatives, and imidoyl sulfonate derivatives.
• R 23 is a straight, branched or cyclic alkyl of 1 to 12 carbon atoms, an aryl of 6 to 12 carbon atoms, or an aralkyl of 7 to 12 carbon atoms;
• M + is iodonium or sulfonium;
• K - is a non-nucleophilic counter-ion; and the letter m is 2 or 3.
• alkyl groups represented by R 23 include methyl, ethyl, propyl, butyl, pentyl, 2-oxocyclohexyl, norbornyl, and adamantyl.
• exemplary aryl groups include phenyl; alkoxyphenyl groups such as p-methoxyphenyl, m-methoxyphenyl, o-methoxyphenyl, ethoxyphenyl, p-tert-butoxyphenyl, and m-tert-butoxyphenyl; and alkylphenyl groups such as 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, ethylphenyl, 4-tert-butylphenyl, 4-butylphenyl, and dimethylphenyl.
• Exemplary aralkyl groups include benzyl and phenethyl.
• the non-nucleophilic counter-ion represented by K - include halide ions such as chloride and bromide; fluoroalkylsulfonate ions such as triflate, 1,1,1-trifluoroethanesulfonate, and nonafluorobutanesulfonate; arylsulfonate ions such as tosylate, benzenesulfonate, 4-fluorobenzenesulfonate, and 1,2,3,4,5-pentafluorobenzenesulfonate; and alkylsulfonate ions such as mesylate and butanesulfonate.
• R 24 and R 25 are straight, branched or cyclic alkyl or halogenated alkyl groups of 1 to 12 carbon atoms, aryl or halogenated aryl groups of 6 to 12 carbon atoms, or aralkyl groups of 7 to 12 carbon atoms.
• alkyl groups represented by R 24 and R 25 include methyl, ethyl, propyl, butyl, amyl, cyclopentyl, cyclohexyl, norbornyl, and adamantyl.
• exemplary halogenated alkyl groups include trifluoromethyl, 1,1,1-trifluoroethyl, 1,1,1-trichloroethyl, and nonafluorobutyl.
• Exemplary aryl groups include phenyl; alkoxyphenyl groups such as p-methoxyphenyl, m-methoxyphenyl, o-methoxy-phenyl, ethoxyphenyl, p-tert-butoxyphenyl, and m-tert-butoxyphenyl; and alkylphenyl groups such as 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, ethylphenyl, 4-tert-butylphenyl, 4-butylphenyl, and dimethylphenyl.
• Exemplary halogenated aryl groups include fluorophenyl, chlorophenyl, and 1,2,3,4,5-pentafluorophenyl.
• Exemplary aralkyl groups include benzyl and phenethyl.
• R 26 , R 27 , and R 28 are straight, branched or cyclic alkyl or halogenated alkyl groups of 1 to 12 carbon atoms, aryl or halogenated aryl groups of 6 to 12 carbon atoms, or aralkyl groups of 7 to 12 carbon atoms.
• R 27 and R 28 may together form a cyclic structure with the proviso that if they form a cyclic structure, each is a straight or branched alkylene group of 1 to 6 carbon atoms.
• alkyl, halogenated alkyl, aryl, halogenated aryl, and aralkyl groups represented by R 26 , R 27 , and R 28 are exemplified by the same groups as mentioned above for R 24 and R 25 .
• alkylene groups represented by R 27 and R 28 include methylene, ethylene, propylene, butylene, and hexylene.
• photoacid generator examples include:
• Preferred among these photoacid generators are onium salts such as triphenylsulfonium trifluoromethanesulfonate, (p-tert-butoxyphenyl)diphenylsulfonium trifluoromethanesulfonate, tris(p-tert-butoxyphenyl)sulfonium trifluoromethanesulfonate, triphenylsulfonium p-toluenesulfonate, (p-tert-butoxyphenyl)diphenylsulfonium p-toluenesulfonate, tris(p-tert-butoxyphenyl)sulfonium p-toluenesulfonate, trinaphthylsulfonium trifluoromethanesulfonate, cyclohexylmethyl(2-oxocyclohexyl)sulfonium trifluoromethanesulfonate,
• photoacid generators may be used singly or in combinations of two or more thereof.
• Onium salts are effective for improving rectangularity, while diazomethane derivatives and glyoxime derivatives are effective for reducing standing waves.
• the combination of an onium salt with a diazomethane or a glyoxime derivative allows for fine adjustment of the profile.
• the photoacid generator is preferably added in an amount of about 0.2 to 15 parts by weight per 100 parts by weight of all the base resins. At less than 0.2 part, the amount of acid generated during exposure would be too small and the sensitivity and resolution be poor, whereas the addition of more than 15 parts would result in a lower transparency and a poor resolution.
• the basic compound used as component (D) is preferably a compound capable of suppressing the rate of diffusion when the acid generated by the photoacid generator diffuses within the resist film.
• the inclusion of this type of basic compound holds down the rate of acid diffusion within the resist film, resulting in better resolution.
• it suppresses changes in sensitivity following exposure, thus reducing substrate and environment dependence, as well as improving the exposure latitude and the pattern profile. See JP-A 5-232706, 5-249683, 5-158239, 5-249662, 5-257282, 5-289322, and 5-289340.
• suitable basic compounds include primary, secondary, and tertiary aliphatic amines, mixed amines, aromatic amines, heterocyclic amines, carboxyl group-bearing nitrogenous compounds, sulfonyl group-bearing nitrogenous compounds, hydroxyl group-bearing nitrogenous compounds, hydroxyphenyl group-bearing nitrogenous compounds, alcoholic nitrogenous compounds, amide derivatives, and imide derivatives.
• Suitable primary aliphatic amines include ammonia, methylamine, ethylamine, n-propylamine, isopropylamine, n-butylamine, iso-butylamine, sec-butylamine, tert-butylamine, pentylamine, tert-amylamine, cyclopentylamine, hexylamine, cyclohexylamine, heptylamine, octylamine, nonylamine, decylamine, dodecylamine, cetylamine, methylenediamine, ethylenediamine, and tetraethylenepentamine.
• Suitable secondary aliphatic amines include dimethylamine, diethylamine, di-n-propylamine, di-iso-propylamine, di-n-butylamine, di-iso-butylamine, di-sec-butylamine, dipentylamine, dicyclopentylamine, dihexylamine, dicyclohexylamine, diheptylamine, dioctylamine, dinonylamine, didecylamine, didodecylamine, dicetylamine, N,N-dimethylmethylenediamine, N,N-dimethylethylenediamine, and N,N-dimethyltetraethylenepentamine.
• Suitable tertiary aliphatic amines include trimethylamine, triethylamine, tri-n-propylamine, tri-iso-propylamine, tri-n-butylamine, tri-iso-butylamine, tri-sec-butylamine, tripentylamine, tricyclopentylamine, trihexylamine, tricyclohexylamine, triheptylamine, trioctylamine, trinonylamine, tridecylamine, tridodecylamine, tricetylamine, N,N,N',N'-tetramethylmethylenediamine, N,N,N',N'-tetramethylethylenediamine, and N,N,N',N'-tetramethyl-tetraethylenepentamine.
• suitable mixed amines include dimethylethylamine, methylethylpropylamine, benzylamine, phenethylamine, and benzyldimethylamine.
• suitable aromatic and heterocyclic amines include aniline derivatives (e.g., aniline, N-methylaniline, N-ethylaniline, N-propylaniline, N,N-dimethylaniline, 2-methylaniline, 3-methylaniline, 4-methylaniline, ethylaniline, propylaniline, trimethylaniline, 2-nitroaniline, 3-nitroaniline, 4-nitroaniline, 2,4-dinitroaniline, 2,6-dinitroaniline, 3,5-dinitroaniline, and N,N-dimethyltoluidine), diphenyl(p-tolyl)amine, methyldiphenylamine, triphenylamine, phenylenediamine, naphthylamine, diaminonaphthalene, pyrrole derivatives (
• suitable carboxyl group-bearing nitrogenous compounds include aminobenzoic acid, indolecarboxylic acid, and amino acid derivatives (e.g. nicotinic acid, alanine, alginine, aspartic acid, glutamic acid, glycine, histidine, isoleucine, glycylleucine, leucine, methionine, phenylalanine, threonine, lysine, 3-aminopyrazine-2-carboxylic acid, and methoxyalanine).
• suitable sulfonyl group-bearing nitrogenous compounds include 3-pyridinesulfonic acid and pyridinium p-toluenesulfonate.
• Suitable hydroxyl group-bearing nitrogenous compounds, hydroxyphenyl group-bearing nitrogenous compounds, and alcoholic nitrogenous compounds include 2-hydroxypyridine, aminocresol, 2,4-quinolinediol, 3-indolemethanol hydrate, monoethanolamine, diethanolamine, triethanolamine, N-ethyldiethanolamine, N,N-diethyl-ethanolamine, triisopropanolamine, 2,2'-iminodiethanol, 2-aminoethanol, 3-amino-1-propanol, 4-amino-1-butanol, 4-(2-hydroxyethyl)morpholine, 2-(2-hydroxyethyl)pyridine, 1-(2-hydroxyethyl)piperazine, 1-[2-(2-hydroxyethoxy)ethyl]piperazine, piperidine ethanol, 1-(2-hydroxyethyl)pyrrolidine, 1-(2-hydroxyethyl)-2-pyrrolidinone, 3-piperidino-1,2-propanedio
• Suitable amide derivatives include formamide, N-methylformamide, N,N-dimethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, propionamide, and benzamide.
• Suitable imide derivatives include phthalimide, succinimide, and maleimide.
• R 29 , R 30 , R 31 , R 35 and R 36 are independently straight, branched or cyclic alkylenes of 1 to 20 carbon atoms;
• R 32 , R 33 , R 34 , R 37 and R 38 are hydrogen, alkyls of 1 to 20 carbon atoms, or amino;
• R 32 and R 33 , R 33 and R 34 , R 32 and R 34 , R 32 with R 33 and R 34 , and R 37 and R 38 may bond together to form rings;
• m, n and o are each integers from 0 to 20, with the proviso that hydrogen is excluded from R 29 , R 30 , R 31 , R 35 and R 36 when m, n and o are equal to 0. Or, when m, n and o are all 0, not all of R 29,30,31,35,36 are H.
• the alkylene groups represented by R 29 , R 30 , R 31 , R 35 and R 36 preferably have 1 to 20 carbon atoms, more preferably 1 to 10 carbon atoms, and most preferably 1 to 8 carbon atoms. Examples include methylene, ethylene, n-propylene, isopropylene, n-butylene, isobutylene, n-pentylene, isopentylene, hexylene, nonylene, decylene, cyclopentylene, and cyclohexylene.
• the alkyl groups represented by R 32 , R 33 , R 34 , R 37 and R 38 preferably have 1 to 20 carbon atoms, more preferably 1 to 8 carbon atoms, and most preferably 1 to 6 carbon atoms, and may be straight, branched or cyclic. Examples include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, hexyl, nonyl, decyl, dodecyl, tridecyl, cyclopentyl, and cyclohexyl.
• R 32 and R 33 , R 33 and R 34 , R 32 and R 34 , R 32 with R 33 and R 34 , and R 37 and R 38 form rings
• the rings preferably have 1 to 20 carbon atoms, more preferably 1 to 8 carbon atoms, and most preferably 1 to 6 carbon atoms, and may have branching alkyl groups of 1 to 6 carbon atoms, and especially 1 to 4 carbon atoms.
• m, n, and o are each integers from 0 to 20, preferably from 1 to 10, and more preferably from 1 to 8.
• Illustrative examples of the compounds of formulas (62) and (63) include tris ⁇ 2-(methoxymethoxy)ethyl ⁇ amine, tris ⁇ 2-(methoxyethoxy)ethyl)amine, tris[2- ⁇ (2-methoxy-ethoxy)methoxy ⁇ ethyl]amine, tris ⁇ 2-(2-methoxyethoxy)ethyl ⁇ amine, tris ⁇ 2-(1-methoxyethoxy)ethyl ⁇ amine, tris ⁇ 2-(1-ethoxyethoxy)ethyl ⁇ amine, tris ⁇ 2-(1-ethoxypropoxy)ethyl ⁇ amine, tris[2- ⁇ (2-hydroxyethoxy)ethoxy ⁇ ethyl]amine, 4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane, 4,7,13,18-tetraoxa-1,10-diazabicyclo[8.
• Especially preferred basic compounds are tertiary amines, aniline derivatives, pyrrolidine derivatives, pyridine derivatives, quinoline derivatives, amino acid derivatives, hydroxyl group-bearing nitrogenous compounds, hydroxyphenyl group-bearing nitrogenous compounds, alcoholic nitrogenous compounds, amide derivatives, imide derivatives, tris ⁇ 2-(methoxymethoxy)ethyl ⁇ amine, tris ⁇ 2-(2-methoxyethoxy)ethyl ⁇ amine, tris[2- ⁇ (2-methoxyethoxy)methyl ⁇ ethyl]amine, and 1-aza-15-crown-5.
• the above-described basic compound may be used singly or in combinations of two or more thereof, and is preferably formulated in an amount of about 0.01 to 2 parts, and especially about 0.01 to 1 part by weight, per 100 parts by weight of the base resin. At less than 0.01 part, the desired effects of the basic compound would not be apparent, while the use of more than 2 parts may result in too low a resolution or sensitivity.
• the dissolution inhibitor (E) is a compound with a molecular weight of up to 3,000 which changes its solubility in an alkaline developer under the action of an acid.
• a compound obtained by partially or entirely substituting acid labile substituents on a phenol or carboxylic acid derivative having a molecular weight of up to 2,500 is added as the dissolution inhibitor.
• the acid labile groups used herein may be either fluorinated acid labile groups as previously mentioned or customary fluorine-free acid labile groups.
• Examples of the phenol or carboxylic acid derivative having a molecular weight of up to 2,500 include 4,4'-(1-methylethylidene)bisphenol, (1,1'-biphenyl-4,4'-diol)-2,2'-methylenebis(4-methylphenol), 4,4-bis(4'-hydroxyphenyl)valeric acid, tris(4-hydroxyphenyl)methane, 1,1,1-tris(4'-hydroxyphenyl)ethane, 1,1,2-tris(4'-hydroxyphenyl)ethane, phenolphthalein, thimolphthalein, 3,3'-difluoro[(1,1'-biphenyl)-4,4'-diol], 3,3',5,5'-tetrafluoro[(1,1'-biphenyl)-4,4'-diol], 4,4'-[2,2,2-trifluoro-1-(trifluoromethyl)ethylidene]bisphenol,
• dissolution inhibitors which are useful herein include 3,3'-5,5'-tetrafluoro[(1,1'-biphenyl)-4,4'-di-t-butoxycarbonyl], 4,4'-[2,2,2-trifluoro-1-(trifluoromethyl)ethylidene]bisphenol-4,4'-di-t-butoxycarbonyl, bis(4-(2'-tetrahydropyranyloxy)phenyl)methane, bis(4-(2'-tetrahydrofuranyloxy)phenyl)methane, bis(4-tert-butoxyphenyl)methane, bis(4-tert-butoxycarbonyloxyphenyl)methane, bis(4-tert-butoxycarbonylmethyloxyphenyl)methane, bis(4-(1'-ethoxy-ethoxy)phenyl)methane, bis(4-(1'-ethoxy-ethoxy)phenyl)
• an appropriate amount of the dissolution inhibitor (E) is up to about 20 parts, and especially up to about 15 parts by weight per 100 parts by weight of the solids in the composition. With more than 20 parts of the dissolution inhibitor, the resist composition becomes less heat resistant because of an increased content of monomer components.
• the resist composition of the invention may include, as an optional ingredient, a surfactant which is commonly used for improving the coating characteristics.
• Optional ingredients may be added in conventional amounts so long as this does not compromise the properties of the material.
• a nonionic surfactant is preferred, examples of which include perfluoroalkyl polyoxyethylene ethanols, fluorinated alkyl esters, perfluoroalkylamine oxides, perfluoroalkyl EO adducts, and fluorinated organosiloxane compounds.
• Illustrative examples include Florade FC-430 and FC-431 from Sumitomo 3M Ltd., Surflon S-141 and S-145 from Asahi Glass Co., Ltd., Unidyne DS-401, DS-403, and DS-451 from Daikin Industries Ltd., Megaface F-8151 from Dainippon Ink & Chemicals, Inc., and X-70-092 and X-70-093 from Shin-Etsu Chemical Co., Ltd.
• Preferred surfactants include Florade FC-430 from Sumitomo 3M Ltd. and X-70-093 from Shin-Etsu Chemical Co., Ltd.
• Pattern formation using the resist composition of the invention may be carried out by a known lithographic technique.
• the resist composition may be applied onto a substrate such as a silicon wafer by spin coating or the like to form a resist film having a thickness of 0.1 to 1.0 pm, which is then pre-baked on a hot plate at 60 to 200°C for 10 seconds to 10 minutes, and preferably at 80 to 150°C for 1/2 to 5 minutes.
• a patterning mask having the desired pattern may then be placed over the resist film, and the film exposed through the mask to an electron beam or to high-energy radiation such as deep-UV rays having a wavelength below 300 nm, an excimer laser, or x-rays in a dose of about 1 to 200 mJ/cm 2 , and preferably about 10 to 100 mJ/cm 2 , then post-exposure baked (PEB) on a hot plate at 60 to 150°C for 10 seconds to 5 minutes, and preferably at 80 to 130°C for 1/2 to 3 minutes.
• PEB post-exposure baked
• aqueous alkali solution such as 0.1 to 5%, and preferably 2 to 3%, tetramethylammonium hydroxide (TMAH), this being done by a conventional method such as dipping, puddling, or spraying for a period of 10 seconds to 3 minutes, and preferably 30 seconds to 2 minutes.
• TMAH tetramethylammonium hydroxide
• the resist composition of the invention is best suited to micro-pattern formation with, in particular, deep-UV rays having a wavelength of 254 to 120 nm, an excimer laser, especially ArF excimer laser (193 nm), F 2 excimer laser (157 nm), Kr 2 excimer laser (146 nm), KrAr excimer laser (134 nm) or Ar 2 excimer laser (121 nm), x-rays, or an electron beam.
• an excimer laser especially ArF excimer laser (193 nm), F 2 excimer laser (157 nm), Kr 2 excimer laser (146 nm), KrAr excimer laser (134 nm) or Ar 2 excimer laser (121 nm), x-rays, or an electron beam.
• the desired pattern may not be obtainable outside the upper and lower limits of the above range.
• resist compositions sensitive to high-energy radiation, with excellent sensitivity and resolution at a wavelength of less than 200 nm, especially less than 170 nm, and excellent plasma etching resistance while the progress of negative conversion is restrained. Because these features of the present resist composition enable its use particularly as a resist having a low absorption at the exposure wavelength of a F 2 excimer laser, a finely defined pattern having sidewalls perpendicular to the substrate can easily be formed, making the resist ideal as a micropatterning material in VLSI fabrication.
• THF for tetrahydrofuran
• AIBN for ⁇ , ⁇ '-azobisisobutyronitrile
• GPC for gel permeation chromatography
• Mw weight average molecular weight
• Mn number average molecular weight
• the reaction mixture was poured into methanol whereupon the polymer precipitated.
• the procedure of dissolving the collected polymer in acetone and pouring into 5 liters of methanol for precipitation was repeated twice.
• the polymer was separated and dried. There was obtained 17.2 g of a white polymer, poly(1,1-bis(trifluoromethyl)ethyl methacrylate).
• This polymer was found to have a Mw of 9,300 g/mol as measured by the light scattering method and a dispersity (Mw/Mn) of 1.85 as determined from the GPC elution curve.
• the reaction mixture was poured into methanol whereupon the polymer precipitated.
• the procedure of dissolving the collected polymer in acetone and pouring into 5 liters of methanol for precipitation was repeated twice.
• the polymer was separated and dried. There was obtained 16.5 g of a white polymer, poly(1,1-bis(heptafluoroisopropyl)ethyl methacrylate).
• This polymer was found to have a Mw of 8,700 g/mol as measured by the light scattering method and a dispersity (Mw/Mn) of 1.80 as determined from the GPC elution curve.
• the reaction mixture was poured into methanol whereupon the polymer precipitated.
• the procedure of dissolving the collected polymer in acetone and pouring into 5 liters of methanol for precipitation was repeated twice.
• the polymer was separated and dried. There was obtained 14.5 g of a white polymer.
• This polymer was found to have a Mw of 8,500 g/mol as measured by the light scattering method and a dispersity (Mw/Mn) of 1.90 as determined from the GPC elution curve.
• Mw/Mn dispersity
• the reaction mixture was poured into methanol whereupon the polymer precipitated.
• the procedure of dissolving the collected polymer in acetone and pouring into 5 liters of methanol for precipitation was repeated twice.
• the polymer was separated and dried. There was obtained 14.0 g of a white polymer.
• This polymer was found to have a Mw of 8,200 g/mol as measured by the light scattering method and a dispersity (Mw/Mn) of 1.95 as determined from the GPC elution curve.
• Mw/Mn dispersity
• a polymer, designated Comparative Polymer 1 was synthesized from a monodisperse polyhydroxystyrene having a molecular weight of 10,000 and a dispersity (Mw/Mn) of 1.10 by substituting tetrahydropyranyl groups for 30% of the hydroxyl groups.
• Comparative Polymer 2 was poly(methyl methacrylate) having a molecular weight of 15,000 and a dispersity of 1.7.
• Comparative Polymer 3 was a novolac polymer having a meta/para ratio of 40/60, a molecular weight of 9,000 and a dispersity of 2.5.
• the polymer solution was spin coated onto a MgF 2 substrate and baked on a hot plate at 100°C for 90 seconds, forming a polymer layer of 300 nm thick on the MgF 2 substrate.
• a vacuum ultraviolet spectrometer VUV200S by Nihon Bunko K.K.
• the polymer layer was measured for transmittance at 248 nm, 193 nm and 157 nm. The results are shown in Table 1.
• Resist solutions were prepared in a conventional manner by formulating the polymer, photoacid generator, basic compound, dissolution inhibitor and solvent in the amounts shown in Table 2.
• DUV-30 (Nissan Chemical K.K.) was coated to form films of 55 nm thick so that the reflectance to KrF light (248 nm) was reduced below 1%.
• the resist solutions were spin coated, then baked on a hot plate at 100°C for 90 seconds to give resist films having a thickness of 300 nm.
• resist materials embodying the invention showed sufficient transparency at the wavelength (157 nm) of F 2 excimer laser. They exhibit positive resist characteristics in that as the dose of KrF exposure increases, the thickness of the resist film left decreases.

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